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a) Find the maximal elements.
b) Find the minimal elements.
c) Is there a greatest element?                                                                                                                       d) Is there a least element?
e) Find all upper bounds of {a, b, c}.
f ) Find the least upper bound of {a, b, c}, if it exists.
g) Find all lower bounds of {f, g, h}.
h) Find the greatest lower bound of {f, g, h}, if it exists.

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a) l and m are the maximal elements as they have no successor

b) a, b and c are the minimal elements as they have no predecessor

c) There is no greatest elements as the 2 maximal elements are incomparable

d) Same as above, a, b and c are minimal and incomparable

e) Upper bounds : a={a,d,i,j,l,h,k,m}   b={b,e,h,k,m,d,i,j,l}   c={c,f,g,k,m,l}  (a,b,c)={k,m,l}

f) Least upper bound of {a,b,c} is k

g) Lower bounds : f={f,c}   g={g,f,c}   h={h,e,b,d,a}

h)  Greatest lower bound of {f,g,h} does not exist as they have no lower bounds in common

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